1. Field
Example embodiments relate to a plasma dry etching apparatus capable of controlling a temperature of an extreme edge of a wafer during a plasma etching process. More particularly, example embodiments relate to a plasma dry etching apparatus including an edge ring with cooling and heating units capable of controlling the surface temperature of an extreme edge of a wafer.
2. Description of Related Art
In general, fabrication of semiconductor devices may involve a process of etching a material layer formed on a wafer using a predetermined etching apparatus, e.g., a process of forming a contact hole through an insulating layer. Etching apparatuses may be classified into dry etching apparatuses and wet etching apparatuses according to the type of an etching process.
For example, a wet etching apparatus is capable of processing a plurality of wafers at the same time. However, some problems, e.g., formation of an undercut, may occur due to isotropic etching characteristics of the wet etching apparatus. For instance, the wet etching apparatus may be inappropriate for an etching process for forming a contact hole.
In comparison, a dry etching apparatus is capable of etching a material layer using plasma, and exhibits anisotropic etching characteristics. Thus, the dry etching apparatus may be widely applied to, e.g., a process of forming line-and-space patterns or contact holes. Dry etching apparatuses may be categorized into physical dry etching apparatuses or chemical dry etching apparatuses.
In a physical dry etching apparatus, ions generated in plasma may be accelerated due to an electrical field to collide with a material layer. Thus, although the physical dry etching apparatus may have good anisotropic etching characteristics, the physical dry etching apparatus may have a poor etch selectivity with respect to a layer disposed under the material layer. In contrast, in the chemical dry etching apparatus, a material layer may be etched due to a chemical reaction of the material layer with radicals generated in plasma. Thus, although the chemical dry etching apparatus may have good selective etching characteristics, the chemical dry etching apparatus may also have isotropic etching characteristics.
In recent years, ion-enhanced plasma etching processes having both good selective etching characteristics and anisotropic etching characteristics have been employed by combining only advantages of the physical and chemical dry etching apparatuses. However, it is still difficult to overcome nonuniform critical linewidth of bars or “not-open” etching failures during formation of line-and-space patterns or contact holes.